Virtual simulation of neuroendoscopic procedures: early clinical experience with ventricular lesions.

[hydrocephalus with stenosis of the aqueduct of sylvius]

Virtual endoscopy (VE ) is a new and promising imaging technology . Applied to neuroendoscopy it allows preoperative simulation of a procedure and evaluation of the individual intraventricular anatomy in selected cases . Along with neuronavigation and real time intraoperative imaging , VE is expected to improve the safety and efficacy of neuroendoscopic procedures .Between April 2003 and February 2004 VE simulation was performed in 13 randomly selected patients subjected to endoscopic procedures . Pathological entities included 4 cases with aqueduct stenosis , 4 with suprasellar arachnoid cysts , 2 tumors of the posterior third ventricle , 1 colloid cyst , 1 hyperplasia of the choroid plexus and 1 case with multiloculated hydrocephalus due to intraventricular septations . In 8 patients VE was accomplished preoperatively , in another 5 it was done after the operation , using data sets from neuronavigation imaging planning in 4 patients , and in one case using postoperative imaging studies . T (1 )-weighted 3 D image sets were acquired on a 1 .5 T GE Genesis SIGNA MR scanner and VE reconstruction was performed using the General Electric Navigator software . The VE images were compared with the real images obtained during the endoscopic procedures and evaluated for their impact on the planning of the operative approach .VE implementation succeeded in all 13 patients . Major neuroanatomic reference structures were easily recognizable in all cases . Membranous structures such as the thinned floor of the third ventricle or cyst walls were identifiable in only 46 % of the cases . In 6 cases (46 %) VE showed anatomical variants and details relevant for the endoscopic procedure that were not identified on conventional MR images .VE has proved to be an important adjunct to the preoperative planning of neuroendoscopic procedures and its routine application is suggested .